The purpose of this study is to examine the possibility that patients with asthma have a disturbance in cellular metabolism of cyclic AMP. The study is based on measurement of cyclic AMP in peripheral blood leukocytes and on evaluation of the responses of these cells to in vivo or in vitro stimulation with various pharmacologic agents. So far, most of our efforts have been centered around acquisition of control data in leukocytes of normal subjects. During the coming year emphasis will be given to evaluation of cyclic AMP data in leukocytes obtained from asthmatic patients. Data will be considered in relation to the severity of symptoms and to the concurrent use of various medications.